The present invention relates to sash windows and in particular to a mounting for a spring counterbalance arrangement used in such sash windows.
Modern sash windows utilise coiled ribbon springs which are mounted within the window jamb channels of the window frame and are arranged to unwind as the sash window is slid and moved within the window frame. The coiled springs provide a counterbalancing force, by virtue of the spring tension of the springs, to counterbalance the weight of the sash window thereby making movement and opening of the window easier. Typically the coiled springs are mounted to the window framed within the vertical window jamb channels either side of the sash window using a mounting/support arrangement. A free end, referred to as a tail, of the spring is connected to a sash shoe slidably located within the window jamb channel. The sash shoe in turn is connected to the sash window, usually towards the lower portion of the sash window. The coiled springs are generally of a constant tension type in which an outer profile of the coil is rotatably held and supported within the spring mounting/support. The spring mounting/support is secured to the window frame within the window jamb channel. An inner end of the spring is free such that the coiled spring can rotate as the spring is unwound and the tail (outer free end) of the spring attached to the sash shoe, is extended and drawn out as the window is moved.
Examples of prior arrangements of the above general type are well-known and common place within the industry. Specific examples are described in the following patents and patent applications:
UK Published Patent application GB 2369644;
UK Published Patent application GB 2380758;
U.S. Pat. No. 6,412,144;
U.S. Pat. No. 6,393,661; and
U.S. Pat. No. 5,365,638.
The text of these patents, and patent applications, are incorporated in their entirety herein by reference.
Modular spring support mountings have been proposed in the prior art, for example in U.S. Pat. No. 5,365,638 in which a plurality of spring support mounting elements, one for each single spring, are stacked on top of one another with each mounting element provided with interengagement formations which when the elements are stacked vertically, and are vertically slid together, interengage and ‘snap fit’ to connect the elements together to form the multiple spring mounting.
With such a modular spring support arrangement spring supports for different numbers of springs, and so different counterbalance forces, can be readily provided by simply adding additional modules to the stack. A modular arrangement is also easier to install within the window jamb channel, with each of the individual modules being separately inserted into the channel and then slid vertically to interengage and stack together.
While the prior modular spring mounting arrangement, as described in U.S. Pat. No. 5,365,638 provides a practical method of mounting and supporting the counterbalance springs, there are a number of problems with such an arrangement, and the modular spring mounting arrangement can be improved generally. In particular, and inherently in the modular arrangement of U.S. Pat. No. 5,365,638, it has been identified that in use the vertical engagement and securing together of the modules is relatively insecure and the individual modules easily become detached from each other once installed, and in particular during opening and closing of the windows. This can lead to jamming of the window, as such a single fixing for the modular arrangement mentioned in U.S. Pat. No. 5,365,638 is not a practical possibility. The modular arrangement of U.S. Pat. No. 5,365,638 is also relatively long and undesirably occupies a significant length of the jamb channel.
It is therefore desirable to provide an improved modular spring mounting arrangement for a sash window counterbalance which addresses the above described problems and/or which offers improvements generally.